Automatic brake



Mair. 27, 1923.

O. B. BJORGE AUTOMATIC BRAKE Filed Jam-14, 1920 I VE/v 70E,

Patented Mar. 27, 1923.

OSCAR B. BJORGE, OF DULUTH, MINNESOTA, ASSIGNOR TO CLYDE-IRON WORKS, OF

DULUTH, MINNESOTA, A CORPORATION OF AUTOMATIC BRAKE.

To all whom it may concern Be it known that I, OSCAR B. BJORGE, a citizen of the United States, and a resident of Duluth, county of St. Louis, and State of Minnesota, have invented a new and useful Improvement in Automatic Brakes, of which the following is a specification, the principle of the invention being herein explained and the best mode in which I have pbntemplated applying that principle, so as to distinguish it from other inventions.

v The present improvements, relating, as indicated, to automatic brakes, have more particular regard to an automatic brake for use in connection with electric or other power driven hoists, where the source of power may be suddenly interrupted while the load hangs suspended. In such case it is of course quite essential that backward rotation of the hoist parts be prevented. The object of the invention, accordingly, is to provide a simple and efficient device for automatically braking such hoist so as to promptly stop any tendency towards such improper reversal in motion.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the means hereinafter fully de scribed and particularly pointed out in the claims, the annexed drawing and the following description setting forth in'detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various mechanical forms in whizh the principle of the invention may be use In said annexed drawing Fig. 1 is an end elevation showing my improved automatic brake as applied to a drum hoist of otherwise familiar construction; Fig. 2 is a side elevation of the same as viewed from the right in Fig. 1; Fig. 3 is a central vertical section taken on the plane indicated by the line 3-3, Fig. 1; and Fig. 4 is a vertical section taken on the plane indicated by the line 4C.4, Fig. 1.

In the aforesaid figures the only portion of the hoist proper that is shown is the shaft 1 which is rotatably journaled in suitable bearings in a frame 2, it being understood that this shaft carries the hoisting drum (not shown), also that suitable means are provided for rotating such shaft to wind or unwind the. cable as desired. In the particular construction shown, the direction Application filed January 14, 1920. Serial Nol 351,398.

but said rocker is otherwisefree to of rotation of the shaft for the purpose of thus winding in the cable, or, in other words, raising the load, is counter-clockwise, as indicated by the arrow in Fig. 1, and the purpose of the braking mechanism forming the feature of interest in the present connection is to automatically prevent rotation of such shaft in the opposite direction. l/Vith this in view a disk or brake wheel 8 is keyed or otherwise firmly secured on the projecting end of shaft 1, and around such disk is fitted a flexible brake band 1. A floating suspension is provided for this band, consisting of an eye-bolt 5 resiliently supported through the medium of a spring 6 from a bracket 7 that projects over the disk from the frame 2. Arrod member 8, conveniently consisting of a bolt, attached at its respective ends to the band 1, passes slida'bly through the eye of bolt 5 asa result of which it will be seen'that the-bandis free to rise and fall as. well as to adjust itself circumferentially about the disk, and yet is held in proper alignment with the disk face. The respectiveends of brake band 4 are attached to a differential rocker 10 that is secured to frame 2 about a pivotal axis 11. The one such end is" adjustably thus attached by being provided with a threaded extension 12 which passes through a swiveled block 13 in therocker, being held therein in desired position by means of nuts 14. v It will further be noted that the points of attachment of the respectiveends of the band .to said rocker are located at unequal distances from the pivotal axis 11, about which the latter turns. A stop 15 on the inner face of the rocker (see Fig. 4) is adapted to engage with the.hoist frame 2, and so limit rotation thereof in one direction, I oscillate about the. axis 11 in question. V I

Pivotally connected at its one end to said rocker 10 is a reach rod 16, the other end of which is in turn pivotally attached to an arm 17 on acollar 18 mounted adjacent the outer face of disk 3 so as to be freely rotatable on shaft 1 except as itsconnection'with said rocker may limit its rotation, This-collar 18 has its lateral faces machined smooth,

and contacting with each such face a' brass washer 19 is inserted for wearing purposes. A secondcollar 20 that is keyed 'onshaft 1, so as to be longitudinally movable therealong lies adj acent the outer washer 19*an'd is pressed thereagainst by means of a spring 21 coiled about said shaft and held in place in its turn by means of a cup-shaped collar 22, the latter being securely fastened to the shaft by means of pin, set screw, or other wise. Said collar 22 is furthermore adjustable longitudinally of the shaft, so that the pressure exerted by spring 21 against collar 20 may be varied. Not only are the rubbing faces of the first-mentioned collar 18 machined smooth, but also the rubbing faces of the other collars, and the portion of the outer face of the disk with which the inner washer 19 contacts, and provision is made to supply these several contacting faces with proper lubrication.

Assuming the spring 21 to be properly compressed and the outermost collar 22 to be securely fixed in its adjusted position on the shaft 1, there will be SUfllClQIlt friction between the faces of the collar 18 and the adjacent faces of disk 3 and collar 20, to cause said collar 18 to tend to rotate in the same direction as theshaft. When such shaft is rotating in itsproper direction, said collar 18 will accordingly pull on reach rod 16 and so draw the longer arm of the rocker 10 towards the disk 3, the eflect being to slacken the brake band a so that it is substantially free from said disk. The stop on the inside of the rocker prevents undue movement of the latter in the direction just indicated, the rocker, and along therewith, the collar 18, becoming stationary. The lubricated sides of such collar can rub against the brass washers 19 continually during such operation in the proper direction without any damage to the parts in question, since the total pressure per square inch exerted thereon by spring 21 is relatively very small.

However, if the source of power is suddenly interrupted, and the load causes shaft 1 to rotate in an opposite direction to that just described, i. e. in a clockwise direction as viewed in Fig. 1, the collar 18 will push on rod 16 and so tend to move rocker 10 likewise in an opposite direction to that previously described, with the result that, due to the inequality in the length of the rocker arms, to which the ends of the brake band are attached, said band is automatically tightened, thereby securely holding disk 3 against further rotation in the direction in question. Theentire hoisting mechanism will accordingly be held stationary and any suspended load prevented from dropping.

'Themechanism just described, it will be seen, permits free, silent and substantially frictionless rotation oflthe brake in proper working direction. Atthe same time perfect mechanical means are provided for applythe the moment thehoisting drum tends to rotate. in .a reverse direction. The stopping ofsuch backward rotation is sure and silent, withoiit, however, any-shock to the mechanism of the hoist, as would be caused by a ratchet and dog, or other similar safety device.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention 1. In mechanism of the character described, the combination with a rotatable member, of means for checking rotation of said member in one direction without interfering with its rotation in the other, said means including a brake-wheel connected. to rotate with said member, a brake-band co-operative with said wheel, a rocker connected with said band so as to contract or expand the same depending upon said rockersdirection of movement, and means j ournaled upon and frictionally connected with said member adapted to actuate said rocker.

2. In mechanism of the character described, the combination with a rotatable member, of means for checking rotation of said member in one direction without interfering with its rotation in the other, said means including a brake-wheel connected to rotate with said member, a brake-band surrounding said wheel, a rocker differentially connected with the ends of said band so as to contract or expand the same depending upon said rockers direction of movement, and means journaled upon and frictionally connected with said member adapted to actuate said rocker.

3. In mechanism of the character described, the combination with a rotatablemember, of means for checking rotation of said member in one direction without interfering with its rotation in the other, said means including a brake-wheel connected to rotate with said member, a brake-band surrounding said wheel, arocker differentially connected with the ends of said band so as to contract or expand the latter depending upon said rockers direction of movement, a collar journaled upon said rotatable memher and frictionally bearing against said wheel, means adapted to maintain a constant pressure of said collar against said wheel, and a rod connecting said collar with said rocker to actuate the latter.

4:. In mechanism of the character, described, the combination with a rotatable member, of means, for checking. rotation of said member in onedirection without interfering with its rotation in the other 1 said means including' .a brake-wheel connected to rotate with said ,member, a brake-band surrounding said wheel, a rocker differentially connected with the eiidso-f said band so as to contract or expand the latter depending upon said rockers direction of movement, a collar journaled upon said rotatable member and frictionally bearing against said Wheel, and a rod connecting said collar with said rocker to actuate the latter.

5. In mechanism of the character described, the combination with a rotatable member, of means for checking rotation of said member in one direction without interfering with its rotation in the other, said means including a brake-wheel connected to rotate with said member, a brake-band surrounding said wheel, a rocker differentially connected with the ends of said band so as to contract or expand the latter depending upon said rockers direction of movement, a collar j ournaled upon said rotatable member and frictionally bearing against said wheel,

means adapted to adjust the pressure of said collar against said wheel, and a rod connecting said collar with said rocker to actuate the latter.

6. In mechanism of the character described, the combination with the shaft of a hoisting drum, of means for checking rotation of said shaft in one direction without interfering with it's rotation in the other, said means including a brake-wheel fixed on said shaft, a brake-band surrounding said Wheel, a rocker differentially connected with the ends of said band so as to contract or expand the latter depending upon said rockers direction of movement, a collar rotatably mounted on said shaft. adjacent said Wheel and adapted to frictionally hear thereagainst, a second collar adjacent said first collar and bearing against the other face thereof, said second collar being longitudinally movable but not rotatable on said shaft, an adjustable mounted spring pressing against said second collar, and a rod connecting said first collar with said rocker to actuate the latter.

Signed by me, this 2 day of January, 1920.

OSCAR B. BJORGE. 

